The present invention relates to a warning method and apparatus, for producing a warning upon the occurrence of a predetermined condition at a monitored location. The invention is particularly useful for monitoring a location against unauthorized intrusions, but may also be used for monitoring other conditions, such as fire, smoke, gas, motion, etc. The invention also relates to a parallel correlator particularly useful in such method and apparatus.
Many systems have been devised for monitoring locations to produce a warning in the event of the occurrence of a predetermined condition; such as an unauthorized intrusion. In general, such known systems include a sensor which senses the predetermined condition, and a signalling device which is actuated to produce an audible and/or visual signal when the predetermined condition is sensed. Such systems, however, suffer from a number of drawbacks, as will be described more particularly below.